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NASA NTRS2002

The Seyfert-Starburst Connection in X-rays: The Data - 1

We analyze X-ray spectra and images of a sample of Seyfert 2 galaxies that unambiguously contain starbursts, based on their optical and UV characteristics. Although all sample members contain active galactic nuclei (AGNs), supermassive black holes or other related processes at the galactic centers alone cannot account for the total X-ray emission in all instances. Eleven of the 12 observed galaxies are significantly resolved with the ROSAT High Resolution Imager, while six of the eight sources observed with the lower resolution Position Sensitive Proportional Counter also appear extended on larger scales. The X-ray emission is extended on physical scales of 10 kpc and greater, which we attribute to starburst-driven outflows and supernova heating of the interstellar medium. Spectrally, a physically motivated composite model of the X-ray emission that includes a heavily absorbed (N(sub H) greater than 10(exp 23)/sq cm) nuclear component (the AGN), power-law-like scattered AGN flux, and a thermal starburst describes this sample well. Half the sample exhibit iron K(alpha) lines, which are typical of AGNs.

Levenson, N. A.↗

NASA NTRS2011

Optical air data systems and methods

Systems and methods for sensing air includes at least one, and in some embodiments three, transceivers for projecting the laser energy as laser radiation to the air. The transceivers are scanned or aligned along several different axes. Each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines air temperatures, wind speeds, and wind directions based on the scattered laser radiation. Applications of the system to wind power site evaluation, wind turbine control, traffic safety, general meteorological monitoring and airport safety are presented.

Caldwell, Loren M.↗

NASA NTRS2006

Consistency of Global Modis Aerosol Optical Depths over Ocean on Terra and Aqua Ceres SSF Datasets

Aerosol retrievals over ocean from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua platforms are available from the Clouds and the Earth's Radiant Energy System (CERES) Single Scanner Footprint (SSF) datasets generated at NASA Langley Research Center (LaRC). Two aerosol products are reported side-by-side. The primary M product is generated by sub-setting and remapping the multi-spectral (0.47-2.1 micrometer) MODIS produced oceanic aerosol (MOD04/MYD04 for Terra/Aqua) onto CERES footprints. M*D04 processing uses cloud screening and aerosol algorithms developed by the MODIS science team. The secondary AVHRR-like A product is generated in only two MODIS bands 1 and 6 (on Aqua, bands 1 and 7). The A processing uses the CERES cloud screening algorithm, and NOAA/NESDIS glint identification, and single-channel aerosol retrieval algorithms. The M and A products have been documented elsewhere and preliminarily compared using 2 weeks of global Terra CERES SSF Edition 1A data in which the M product was based on MOD04 collection 3. In this study, the comparisons between the M and A aerosol optical depths (AOD) in MODIS band 1 (0.64 micrometers), tau(sub 1M) and tau(sub 1A) are re-examined using 9 days of global CERES SSF Terra Edition 2A and Aqua Edition 1B data from 13 - 21 October 2002, and extended to include cross-platform comparisons. The M and A products on the new CERES SSF release are generated using the same aerosol algorithms as before, but with different preprocessing and sampling procedures, lending themselves to a simple sensitivity check to non-aerosol factors. Both tau(sub 1M) and tau(sub 1A) generally compare well across platforms. However, the M product shows some differences, which increase with ambient cloud amount and towards the solar side of the orbit. Three types of comparisons conducted in this study - cross-platform, cross-product, and cross-release confirm the previously made observation that the major area for improvement in the current aerosol processing lies in a more formalized and standardized sampling (and most importantly, cloud screening) whereas optimization of the aerosol algorithm is deemed to be an important yet less critical element.

Ignatov, Alexander↗

NASA NTRS2000

Electrodynamic Balance for Studies of Cosmic Dust Particles

Knowledge of the formation and distribution of interstellar, interplanetary, and planetary dust grains, and their physical, chemical and optical characteristics provide valuable information about many issues dealing with the origin and formation of the solar system bodies, interplanetary and interstellar environments as well as various industrial processes. Understanding the microphysics of individual grains and their interaction with the surrounding, environment is key to properly model various conditions and interpret existing data. The theory and models of individual dust grains are well developed for environments that vary from dense planetary atmospheres to dusty plasmas to diffuse environments such as interplanetary space. However, experimental investigations of individual dust grains in equilibrium are less common, perhaps due to the difficulty of these experiments. Laboratory measurements of dust grains have primarily measured ensemble properties or transient properties of single grains. A technique developed in the 1950's for ion spectroscopy, generally referred to as a quadrupole trap has recently been employed as an electrodynamic balance to investigate single micron-sized dust grains and for atmospheric aerosol research. A description of the theoretical basis and the experimental setup of the electrodynamic balance being developed in our laboratory are given. This laboratory technique lends itself to many applications that relate to planetary atmospheres, heliospheric environments, pre-stellar and pre-planetary conditions, and industrial settings. We present results from some recent experiments carried out to investigate the equilibrium potential of dust grains exposed to far ultraviolet light or to an electron beam. Some future experiments using an electrodynamic balance to investigate the optical characteristics, and condensation process involving dust grains in various astrophysical environments are discussed.

Spann, J. F.↗

NASA NTRS2012

Sensitivity of Ocean Reflectance Inversion Models for Identifying and Discriminating Between Phytoplankton Functional Groups

The daily, synoptic images provided by satellite ocean color instruments provide viable data streams for observing changes in the biogeochemistrY of marine ecosystems. Ocean reflectance inversion models (ORMs) provide a common mechanism for inverting the "color" of the water observed a satellite into marine inherent optical properties (lOPs) through a combination of empiricism and radiative transfer theory. lOPs, namely the spectral absorption and scattering characteristics of ocean water and its dissolved and particulate constituents, describe the contents of the upper ocean, information critical for furthering scientific understanding of biogeochemical oceanic processes. Many recent studies inferred marine particle sizes and discriminated between phytoplankton functional groups using remotely-sensed lOPs. While all demonstrated the viability of their approaches, few described the vertical distributions of the water column constituents under consideration and, thus, failed to report the biophysical conditions under which their model performed (e.g., the depth and thickness of the phytoplankton bloom(s)). We developed an ORM to remotely identifY Noctiluca miliaris and other phytoplankton functional types using satellite ocean color data records collected in the northern Arabian Sea. Here, we present results from analyses designed to evaluate the applicability and sensitivity of the ORM to varied biophysical conditions. Specifically, we: (1) synthesized a series of vertical profiles of spectral inherent optical properties that represent a wide variety of bio-optical conditions for the northern Arabian Sea under aN Miliaris bloom; (2) generated spectral remote-sensing reflectances from these profiles using Hydrolight; and, (3) applied the ORM to the synthesized reflectances to estimate the relative concentrations of diatoms and N Miliaris for each example. By comparing the estimates from the inversion model to those from synthesized vertical profiles, we were able to identifY those bio-optical conditions under which the inversion model performs both well and poorly.

Werdell, P. Jeremy↗

NASA NTRS2011

JWST Wavefront Control Toolbox

A Matlab-based toolbox has been developed for the wavefront control and optimization of segmented optical surfaces to correct for possible misalignments of James Webb Space Telescope (JWST) using influence functions. The toolbox employs both iterative and non-iterative methods to converge to an optimal solution by minimizing the cost function. The toolbox could be used in either of constrained and unconstrained optimizations. The control process involves 1 to 7 degrees-of-freedom perturbations per segment of primary mirror in addition to the 5 degrees of freedom of secondary mirror. The toolbox consists of a series of Matlab/Simulink functions and modules, developed based on a "wrapper" approach, that handles the interface and data flow between existing commercial optical modeling software packages such as Zemax and Code V. The limitations of the algorithm are dictated by the constraints of the moving parts in the mirrors.

Shin, Shahram Ron↗

NASA NTRS1975

The Large Space Telescope - A new adventure

A description is presented of the Large Space Telescope (LST), which will be launched in 1982 and can accomodate four scientific instruments at any given time, permitting spectrographic and photometric observations between 1200 A in the UV and 1 mm in the IR. Basic elements of the LST are the optical telescope assembly, the scientific instruments (cameras, spectrographs, photometers, and an astrometer), and the support-systems module. Developmental as well as observational considerations are discussed, including various approaches to testing, maintenance, data transmission and processing, instrument calibration, housekeeping, and refurbishment. A possible mission scenario is outlined.

Friedlaender, F. M.↗

NASA NTRS1989

Some new results in the investigation of the middle atmosphere from space using the daytime horizon scanning method

The results of the restoration of the optical parameters of the El Chichon aerosol cloud at Lambda 2.2 micron are presented. The eight channel teleradiometer FAZA for visible and near infrared spectral regions is described in some detail. Mathematical aspects of data processing for the ill-posed problems are discussed. The results of the restoration of the volume emission rate of the molecular oxygen on Lambda 1.27 micron in the middle atmosphere and of the aerosol on Lambda 0.84 micron are presented.

Room, R.↗

NASA NTRS2021

Evaluation of vicarious calibration for airborne sensors using RadCalNet

Vicarious calibration approaches using in-situ measurements are key techniques applied to on-orbit remote sensors. The in-situ measurements have advantages in terms of traceability and quantifiable accuracy that make them ideal for inter-consistency studies of on-orbit sensors. The Committee on Earth Observation Satellites Working Group on Calibration and Validation Infrared Visible Optical Sensors initiated the Radiometric Calibration Network (RadCalNet) to provide automated surface and top-of-atmosphere (TOA) reflectance data from multiple participating ground sites to the worldwide user community. RadCalNet standardizes protocols for collecting data, processes TOA reflectance, and provides International System of Units traceable uncertainty budgets for the five currently operating sites. RadCalNet data from the Railroad Valley Playa, Nevada, site was used to provide an SI-traceable, absolute radiometric calibration of the Enhanced MODIS Airborne Simulator as part of an overflight of opportunity during the FIREX-AQ campaign. The results shown here demonstrate the utility of RadCalNet data for absolute radiometric calibration of airborne imagers making flights of opportunity without the need for coordination with a field validation team.

Sensors↗

NASA NTRS2022

Machine learning for Deep Space Network antenna motions detection

Highly stable frequency and timing standards are essential for deep-space missions and radio science. At the NASA Deep Space Network (DSN), these standards are distributed through a network of underground fiber cables to support several Goldstone antennas. Independently developed frequency-measuring instruments generate tremendous quantities of data to monitor and validate the antennas’ stringent frequency requirements. In this paper, we propose a lightweight processing tool capable of detecting disturbances on the frequency signal caused by DSN antenna motions. Our training data is sampled from the movement log of the antenna of interest and the generated data from the fiber optic metrology instrument linked to the antenna. We demonstrate that a convolutional neural network (CNN) model can achieve high accuracies on classifying instances of antenna movements and is an effective predictor when used iteratively on longer, variable stretches of metrology data. The simplicity, low training cost, and high accuracies of our model strongly suggest its efficacy in identifying and troubleshooting frequency disturbances caused by the antenna.

Yi, Lin↗

NASA NTRS2002

Formation of Brown Dwarfs LTSA 2001

The goals of the work funded by this grant are: (1) The measurement of the mass function and minimum mass of free-floating brown dwarfs down to the mass of Jupiter; (2) The measurement of the frequency of wide brown dwarf and planetary companions down to the mass of Jupiter as function of primary mass (0.02-2 Msun), age (1-10 Myr), and environment (clusters vs. dispersed regions). For the first objective, we have completed the design of guaranteed SIRTF observations of nearby star-forming regions and now await the launch of the mission in April 2003. In support of these upcoming observations, in the fall of 2002 we obtained optical spectroscopy at the MMT and the 1.5-meter telescope at Fred Lawrence Whipple Observatory for candidate young low-mass stars and brown dwarfs in the IC348 and Taurus star-forming regions. Two papers that include these data in new measurements of the mass functions in these regions are near completion and will be submitted for publication to the Astrophysical Journal in January. We have also proposed deep optical and near-IR imaging of the SIRTF fields in the IC348, Chamaeleon, and Ophiuchus star-forming regions with the MMT, Magellan, and Gemini North telescopes in early 2003. For the second objective, we have used deep HST WFPC2 images to search for young giant planets and brown dwarfs around approximately 100 low-mass stars and brown dwarfs in the nearby cluster IC 348. We have completed all data reduction and have checked these data for candidate companions. We are in the process of writing a paper that describes these candidate companions and presents the companion detection limits that were achieved with HST. We will attempt followup spectroscopy of the most promising candidate companions to confirm their nature as cool companions rather than background field stars during the commissioning of the facility adaptive optics system for the Gemini North telescope early in 2003. In addition, in SIRTF guaranteed time observations we plan to search for wide substellar companions (greater than 10 inches) around the youngest nearby field stars (ages of 30-100 Myr, d less than 30 pc). We have proposed to use Keck adaptive optics imaging to search these same stars for close-in planets and brown dwarfs at 0.1-l0 inches, which will perfectly complement our SIRTF observations.

Luhman, Kevin L.↗

NASA NTRS2002

Using Multiwavelength Observations to Determine the Black Hole Mass and Accretion Rate in the Type 1 Seyfert Galaxy NGC 5548

We model the spectral energy distribution of the type 1 Seyfert galaxy NGC 5548, fitting data from simultaneous optical, UV, and X-ray monitoring observations. We assume a geometry consisting of a hot central Comptonizing region surrounded by a thin accretion disk. The properties of the disk and the hot central region are determined by the feedback occurring between the hot Comptonizing region and thermal reprocessing in the disk that, along with viscous dissipation, provides the seed photons for the Comptonization process. The constraints imposed upon this model by the multiwavelength data allow us to derive limits on the central black hole mass, Mu is approximately or less than 2x10(exp 7) solar mass, the accretion rate, Mu is approximately or less than 2.5x10(exp 5) sq solar mass per year/Mu, and the radius of the transition region between the thin outer disk and the geometrically thick, hot inner region, is approximately 2-5x10(exp 14) cm.

Chiang, James↗

NASA NTRS2020

Thermal Decomposition of the Murchison CM2 Carbonaceous Chondrite: Implications of Space Weathering Processes for Sample Return Missions

Primitive carbonaceous asteroids are the target bodies for the JAXA Hayabusa2 mission to Ryugu and the NASA OSIRIS-REx mission to Bennu. Both asteroids share spectral characteristics of CI/CM type carbonaceous chondrites. Ryugu, in particular, appears to have undergone thermal processing that has modified its spectral properties. The nature and extent of space weathering processes on the surfaces of Bennu and Ryugu are under active investigation using remote sensing data from the missions [4] and through laboratory studies on analog materials. The analog studies are needed in order to understand the mineralogical and chemical changes that occur in space weathered samples that give rise to the observed optical effects measured by remote-sensing and to prepare for the analysis of returned samples. The space weathering effects of micrometeorite impact and solar wind irradiation on primitive carbonaceous chondrites have been simulated by analog studies on the Murchison CM2 chondrite. We performed a coordinated mineralogical, chemical and spectroscopic study to examine in detail the effects of thermal metamorphism on Murchison samples as an analog to processes that may have occurred on Ryugu. The bulk measurements including X-ray diffraction (XRD), Mössbauer spectroscopy, UV-VIS-NIR spectroscopy, thermogravimetric analysis, and evolved gas analysis are reported in a companion paper. Here we report on our preliminary nanoscale mineralogical and chemical analyses of pre- and post-heated Murchison samples using multiple electron beam techniques to understand how the mineralogical, chemical, and physical characteristics of carbonaceous chondrites change with increasing thermal effects.

Lee, S.↗

NASA NTRSDate not supplied

Analysis of CO Transport from Australia Fires and Its Impact to Ozone, Water Vapor and Clouds Using CrIS Single-Field-of-View Sounder Products and Other Remote Sensing and MERRA-2 Reanalysis Data

Australia’s unprecedented fire disasters at the end of 2019 to early 2020 emitted huge amounts of carbon monoxide (CO) and fire aerosol particles, and the long-range transport of the smoke plumes poses great impact to climate change, such as altering the Antarctic ozone (O3) hole. Spaceborne observations from satellites have been proven successful in monitoring CO from wildfires in the past decade and can be used to examine the associated CO transport. The primary remote sensing data used in this study is the Single Field of View (SFOV) Sounder Atmospheric Product (SiFSAP) derived from the Cross-track Infrared Sounder (CrIS) on SNPP, a new product that will be generated at NASA and released to the public in a few months. SiFSAP has a high spatial resolution of ~14 km and includes atmospheric profiles of temperature, water vapor, CO, O3, as well as cloud products, and as the SiFSAP algorithm performs both day- and night-time retrievals, it provides an additional observation for night-time in comparison to the day-time-only solar polar satellite instruments such as MOPPIT, OMPS, and TROPOMI. Most recent significant improvements in the quality of this product plus its good spatial resolution (better than most global weather and climate models) enable us to conduct process-oriented analysis of CO transport, and the variation of water vapor, O3 and clouds (optical depth, effective radius and cloud height) within and around the fire plumes. The wind fields from MERRA-2 reanalysis will be used to help characterize the transport. Other remote sensing data, such as CO from AIRS, MOPPIT and TROPOMI, O3 from OMPS and TROPOMI, as well as the UV aerosol index from OMI and OMPS, will be used and compared with SiFSAP sounder products. Cross-validation of CO and O3 from these different sensors with the corresponding MERRA-2 products will also be carried out. Along the plume transport path, some enhancement of O3 and correlation between fire aerosol, cloud optical depth and water vapor have been found but need further investigation. Using the transport of fire plumes over the Southern Pacific Ocean as a unique testbed, this study will demonstrate the trace species monitoring capability of current satellite observations, in particular, for CO and O3, and hopefully, it will provide some insight on the impacts on fire emissions on air quality and climate.

Xiaozhen (Shawn) Xiong↗

NASA NTRS1991

Stratospheric aerosol optical depth observed by the Stratospheric Aerosol and Gas Experiment. II - Decay of the El Chichon and Ruiz volcanic perturbations

The decay of the El Chichon perturbation to the optical depth of stratospheric aerosols at 1.02 micron, 0.525 micron, and 0.453 micron is calculated from the Stratospheric Aerosol and Gas Experiment II (SAGE II) data set for the period December 1984 to December 1988. It is found that the perturbed optical depths at middle and higher latitudes of both hemispheres exhibited an exponential decay superimposed by a seasonal oscillation with a maximum and a minimum occurring in local winter and local summer, respectively. Microphysical processes and variation of the tropopause height alone cannot explain this seasonal change of optical depth. The magnitudes of the exponential component at higher latitudes were, in general, larger than those at lower latitudes. For optical depths in tropical regions, the seasonal oscillations were small and were disturbed by the eruption of Nevado del Ruiz on November 13, 1985. The increase in the ratio of optical depth at 0.525 micron to that at 1.02 micron from about 2.0 at the beginning of 1985 to about 3.5 at the end of 1988 indicates the average size of aerosol particles in the stratosphere is diminishing since the eruption of El Chichon. The 1/e folding time for El Chichon decay derived from the SAGE II data set is in reasonably good agreement with those derived by other methods.

Yue, G. K.↗

NASA NTRS1996

Ocean observations with EOS/MODIS: Algorithm development and post launch studies

Several significant accomplishments were made during the present reporting period. We have completed our basic study of using the 1.38 micron MODIS band for removal of the effects of thin cirrus clouds and stratospheric aerosol. The results suggest that it should be possible to correct imagery for thin cirrus clouds with optical thicknesses as large as 0.5 to 1.0. We have also acquired reflectance data for oceanic whitecaps during a cruise on the RV Malcolm Baldrige in the Gulf of Mexico. The reflectance spectrum of whitecaps was found to be similar to that for breaking waves in the surf zone measured by Frouin, Schwindling and Deschamps. We installed a CIMEL sun photometer at Fort Jefferson on the Dry Tortugas off Key West in the Gulf of Mexico. The instrument has yielded a continuous stream of data since February. It shows that the aerosol optical thickness at 669 nm is often less than 0.1 in winter. This suggests that the Southern Gulf of Mexico will be an excellent winter site for vicarious calibration. In addition, we completed a study of the effect of vicarious calibration, i.e., the accuracy with which the radiance at the top of the atmosphere (TOA) can be predicted from measurement of the sky radiance at the bottom of the atmosphere (BOA). The results suggest that the neglect of polarization in the aerosol optical property inversion algorithm and in the prediction code for the TOA radiances is the largest error associated with the radiative transfer process. Overall, the study showed that the accuracy of the TOA radiance prediction is now limited by the racliometric calibration error in the sky radiometer. Finally, considerable coccolith light scattering data were obtained in the Gulf of Maine with a flow-through instrument, along with data relating to calcite concentration and the rate of calcite production.

Gordan, Howard R.↗

NASA NTRS1995

Parameterization and scaling of arctic ice conditions in the context of ice-atmospheric processes

The goals of this project are to observe how the open water/thin ice fraction in a high-concentration ice pack responds to different short-period atmospheric forcings, and how this response is represented in different scales of observation. The objectives can be summarized as follows: determine the feasibility and accuracy of ice concentration and ice typing by ERS-1 SAR backscatter data, and whether SAR data might be used to calibrate concentration estimates from optical and massive-microwave sensors; investigate methods to integrate SAR data with other satellite data for turbulent heat flux parameterization at the ocean/atmosphere interface; determine how the development and evolution of open water/thin ice areas within the interior ice pack vary under different atmospheric synoptic regimes; compare how open-water/thin ice fractions estimated from large-area divergence measurements differ from fractions determined by summing localized openings in the pack; relate these questions of scale and process to methods of observation, modeling, and averaging over time and space.

Barry, R. G.↗

NASA NTRS1985

Advanced local area network concepts

Development of a good model of the data traffic requirements for Local Area Networks (LANs) onboard the Space Station is the driving problem in this work. A parameterized workload model is under development. An analysis contract has been started specifically to capture the distributed processing requirements for the Space Station and then to develop a top level model to simulate how various processing scenarios can handle the workload and what data communication patterns result. A summary of the Local Area Network Extendsible Simulator 2 Requirements Specification and excerpts from a grant report on the topological design of fiber optic local area networks with application to Expressnet are given.

Grant, Terry↗